The present invention relates more particularly to a method and to a system for determining data representative of a sound nuisance level that would be felt by a human situated out of a rotorcraft.
A considerable amount of work has been performed in an attempt to control the sound level produced by an aircraft and to attenuate the corresponding perceived nuisance.
Various systems relating to the noise generated by an aircraft are described in the following patents: US 2005/0098681, U.S. Pat. No. 6,198,991, EP 0 945 841, JP 10 038 671, and JP 6 206 594.
Patents FR-2 868 561 and WO 2005/100153 describe a method of minimizing the noise emitted while a rotorcraft is taking off or landing, and they also describe a device for implementing the method.
In the method described, various sound levels are measured, and where appropriate weighted, as detected by a plurality of microphones secured outside the rotorcraft, and for various configurations that differ in terms of rotorcraft mass and rotor speeds of rotation.
Thereafter, diagrams are drawn up of acoustic “isolevels” in a coordinate system based on path air speed and on vertical air speed, while making corrections for noise and apparent mass.
Thereafter, flight ranges are determined as a function of the corresponding diagrams so as to correspond to an acceptable maximum noise level.
During a flight, piloting instructions are determined on the basis of measuring two air speed components, of the instantaneous mass of the rotorcraft, and of the previously-recorded flight ranges; these instructions are displayed on a screen, and where appropriate they are transmitted to an autopilot.
Although that method is advantageous, it does not enable the pilot to take account of the nuisance that is liable to result for a human from the sound level of the rotorcraft.
The present invention seeks to remedy this shortcoming.
The invention also seeks to provide an on-board system for determining and informing the pilot of an aircraft, in real time, about the nuisance level likely to be caused by the aircraft in operation, in a manner that is simplified and/or improved, and/or that remedies, at least in part, the shortcomings or the drawbacks of prior systems.